Data processing circuit, physical quantity detection circuit, physical quantity detection device, electronic apparatus, and moving object

ABSTRACT

A data processing circuit includes an interpolation circuit that performs an interpolation process on an input digital signal and outputs interpolated data subjected to the interpolation process. A reading request signal making a request for outputting the interpolated data is input, and the interpolation circuit performs the interpolation process based on the digital signal input earlier than a timing at which the reading request signal is input.

BACKGROUND

1. Technical Field

The present invention relates to a data processing circuit, a physicalquantity detection circuit, a physical quantity detection device, anelectronic apparatus, and a moving object.

2. Related Art

At present, physical quantity detection devices capable of detectingvarious physical quantities, such as acceleration sensors detectingacceleration and gyro sensors detecting angular velocities, are widelyused for various systems or electronic apparatuses. Physical quantitydetection devices in which A/D conversion circuits convert physicalquantity detection signals (analog signals) into digital signals andoutput detection information as digital data can output digital signalwith high noise resistance. Therefore, systems that include the physicalquantity detection devices and MCUs receiving digital data andperforming calculation can ensure high reliability.

In the systems, when the MCUs do not synchronize frequencies forsampling the digital data with sampling frequencies of A/D conversioncircuits included in the physical quantity detection devices, there is aproblem that folding noise of signals occurs by reception (sampling) ofthe MCUs. JP-A-2006-345508 discloses a frequency conversion method ofinitializing a circuit from a sampling rate ratio of an input to anoutput and performing optimum over/under sampling and filter processing.

However, in the frequency conversion method disclosed inJP-A-2006-345508, it is necessary to know the sampling rate ratio.Therefore, when the sampling rate ratio can be comprehended in advance,the frequency conversion method is effective. However, in an event inwhich the MCU acquires data at an irregular timing, it is difficult tocomprehend an exact sampling rate ratio and the frequency conversionmethod is not necessarily an effective method.

SUMMARY

An advantage of some aspects of the invention is to provide a dataprocessing circuit capable of reducing occurrence of folding noise in anoutput signal even when an input timing of a digital signal isasynchronous with a reading request timing. Another advantage of someaspects of the invention is to provide a physical quantity detectioncircuit capable of reducing occurrence of folding noise in an outputsignal even when a sampling timing of an analog signal related to aphysical quantity is asynchronous with a reading request timing. Stillanother advantage of some aspects of the invention is to provide aphysical quantity detection device using the physical quantity detectioncircuit. Yet another advantage of some aspects of the invention is toprovide an electronic apparatus and a moving object using the physicalquantity detection device.

The invention can be implemented as the following forms or applicationexamples.

APPLICATION EXAMPLE 1

A data processing circuit according to this application example includesan interpolation circuit that performs an interpolation process on aninput digital signal and outputs interpolated data subjected to theinterpolation process. A reading request signal making a request foroutputting the interpolated data is input, and the interpolation circuitperforms the interpolation process based on the digital signal inputearlier than a timing at which the reading request signal is input.

In the data processing circuit according to this application example, adigital signal recently input at the timing at which the reading requestsignal is input is not output, but the interpolated data subjected tothe interpolation process based on the previously input digital signalis output. Even when the input timing of the digital signal isasynchronous with the reading request timing, it is possible to reduceoccurrence of folding noise to an output signal.

APPLICATION EXAMPLE 2

The data processing circuit according to the application example mayfurther include an interface circuit. The interface circuit may outputthe reading request signal according to an input communication signal.The interpolation circuit may output the interpolated data in responseto the reading request signal. The interpolated data may be output viathe interface circuit.

In the data processing circuit according to this application example,the interpolated data is output in response to the reading requestsignal synchronous with the communication signal input via the interfacecircuit. Therefore, even when the input timing of the digital signal isasynchronous with the input timing of the communication signal, it ispossible to reduce occurrence of folding noise to a signal output viathe interface circuit.

APPLICATION EXAMPLE 3

In the data processing circuit according to the application example, theinterpolation circuit may perform the interpolation process based on atime from an input timing of the digital signal to an input timing ofthe reading request signal and a plurality of the digital signals inputearlier than the input timing of the digital signal.

In the data processing circuit according to this application example,the interpolation circuit can generate the appropriate interpolated dataaccording to the time from the input timing of the digital signal to theinput timing of the reading request signal. It is possible to reduceoccurrence of folding noise to the output signal.

APPLICATION EXAMPLE 4

In the data processing circuit according to the application example, theinterpolation circuit may perform the interpolation process by a cubicinterpolation method.

In the data processing circuit according to this application example,the interpolation circuit can perform the correction process withrelatively high accuracy by the cubic interpolation method (for example,a Bi-Cubic method). It is possible to reduce occurrence of folding noiseto the output signal.

APPLICATION EXAMPLE 5

In the data processing circuit according to the application example, theinterpolation circuit may perform the interpolation process in responseto the reading request signal.

In the data processing circuit according to this application example,the interpolation circuit does not perform the correction process at alltimes, but performs the interpolation process in response to the readingrequest signal. Therefore, it is possible to reduce power consumption.

APPLICATION EXAMPLE 6

In the data processing circuit according to the application example, theinterpolation circuit may store data related to a relation between acalculation coefficient of the interpolation process and a timing atwhich the reading request signal is input.

In the data processing circuit according to this application example, itis not necessary for the interpolation circuit to calculate thecalculation coefficient of the interpolation process using the storeddata. Therefore, the correction process can be performed in a short timeusing a circuit (for example, an addition circuit) with a small sizeinstead of a circuit (for example, a multiplier) with a large size.

APPLICATION EXAMPLE 7

A physical quantity detection circuit according to this applicationexample includes: an A/D conversion circuit that performs A/D conversionon an analog signal related to a physical quantity; a digital filtercircuit to which a signal from the A/D conversion circuit is input; aninterpolation circuit to which a digital signal from the digital filtercircuit is input, which performs an interpolation process on the digitalsignal, to which a reading request signal making a request foroutputting interpolated data subjected to the interpolation process isinput, and which performs the interpolation process based on the digitalsignal input earlier than a timing at which the reading request signalis input; and an interface circuit that outputs the reading requestsignal according to an input communication signal. The interpolated datais output via the interface circuit.

In the physical quantity detection circuit according to this applicationexample, the interpolation circuit does not output the digital signalobtained when the A/D conversion circuit recently samples and convertsthe analog signal related to the physical quantity at the timing atwhich the reading request signal synchronous with the communicationsignal input via the interface circuit is input, but outputs theinterpolated data subjected to the interpolation process based on thedigital signal obtained when the A/D conversion circuit previouslysamples and the convert the analog signal. Accordingly, even when thesampling timing by the A/D conversion circuit is asynchronous with thereading request timing based on the communication signal, it is possibleto reduce occurrence of folding noise to the output signal.

APPLICATION EXAMPLE 8

In the physical quantity detection circuit according to the applicationexample, the interpolation circuit may perform the interpolation processin response to the reading request signal.

In the physical quantity detection circuit according to this applicationexample, the interpolation circuit does not perform the correctionprocess at all times, but performs the interpolation process in responseto the reading request signal. Therefore, it is possible to reduce powerconsumption.

APPLICATION EXAMPLE 9

In the physical quantity detection circuit according to the applicationexample, the interpolation circuit may store data related to a relationbetween a calculation coefficient of the interpolation process and atiming at which the reading request signal is input.

In the physical quantity detection circuit according to this applicationexample, it is not necessary for the interpolation circuit to calculatethe calculation coefficient of the interpolation process using thestored data. Therefore, the correction process can be performed in ashort time using a circuit (for example, an addition circuit) with asmall size instead of a circuit (for example, a multiplier) with a largesize.

APPLICATION EXAMPLE 10

A physical quantity detection device according to this applicationexample includes: any of the physical quantity detection circuitsdescribed above; and a physical quantity detection element. An analogsignal is a signal output from the physical quantity detection element.

According to this application example, it is possible to provide thephysical quantity detection device capable of reducing occurrence offolding noise to the output signal even when the sampling timing of theanalog signal related to the physical quantity is asynchronous with thereading request timing.

APPLICATION EXAMPLE 11

In the physical quantity detection device according to the applicationexample, the physical quantity detection element may be an inertialsensor.

According to this application example, it is possible to provide thephysical quantity detection device capable of reducing occurrence offolding noise to the output signal even when the sampling timing of theanalog signal related to an inertial quantity is asynchronous with thereading request timing.

APPLICATION EXAMPLE 12

An electronic apparatus according to this application example includes:any of the physical quantity detection devices described above; and acontrol device that transmits a communication signal.

APPLICATION EXAMPLE 13

A moving object according to this application example includes: any ofthe physical quantity detection devices described above; and a controldevice that transmits a communication signal.

According to these application examples, the physical quantity detectiondevice is used which is capable of reducing occurrence of folding noiseto the output signal even when the sampling timing of the analog signalrelated to a physical quantity is asynchronous with the reading requesttiming. Therefore, it is possible to also realize the electronicapparatus and the moving object with high reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a diagram illustrating an example of the configuration of aphysical quantity detection device according to an embodiment.

FIG. 2 is a plan view illustrating a vibrator element of a physicalquantity detection element.

FIG. 3 is a diagram illustrating an operation of the physical quantitydetection element.

FIG. 4 is a diagram illustrating an operation of the physical quantitydetection element.

FIG. 5 is a diagram illustrating an example of the configuration of adrive circuit.

FIG. 6 is a diagram illustrating an example of the configuration of adetection circuit.

FIG. 7 is a diagram illustrating an example of the configuration of adata processing circuit.

FIG. 8 is a diagram illustrating a Bi-Cubic method.

FIG. 9 is a diagram illustrating examples of timing charts of a masterclock signal, a counter output signal, a sampling clock signal, and areading request signal.

FIG. 10 is a diagram illustrating an example of a lookup table accordingto a first embodiment.

FIG. 11 is a diagram illustrating an example of the configuration of acalculation circuit according to a second embodiment.

FIG. 12 is a diagram illustrating an example of a lookup table accordingto the second embodiment.

FIG. 13 is a functional block diagram illustrating an example of theconfiguration of an electronic apparatus according to the embodiment.

FIG. 14 is a diagram illustrating an example of the outer appearance ofthe electronic apparatus according to an embodiment.

FIG. 15 is a diagram illustrating an example of a moving objectaccording to the embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, preferred embodiments of the invention will be described indetail with reference to the drawings. Content of the inventiondescribed in the appended claims is not inappropriately limited in theembodiments to be described below. All of the configurations to bedescribed below are not prerequisites of the invention.

Hereinafter, a physical quantity detection device (angular velocitydetection device) detecting an angular velocity as a physical quantitywill be described as an example.

1. Physical Quantity Device

1-1. First Embodiment

Configuration of Physical Quantity Detection Device

FIG. 1 is a functional block diagram illustrating a physical quantitydetection device (angular velocity detection device) according to anembodiment. A physical quantity detection device 1 according to theembodiment is configured to include a physical quantity detectionelement (sensor element) 100 that outputs an analog signal related to aphysical quantity and a physical quantity detection circuit 200.

The physical quantity detection element 100 includes a vibrator elementin which a drive electrode and a detection electrode are disposed. Ingeneral, the vibrator element is sealed to a package in whichairtightness is ensured in order to reduce impedance of the vibratorelement as much as possible and improve oscillation efficiency. In theembodiment, the physical quantity detection element 100 includes aso-called double T type vibrator element that includes two T type drivevibration arms.

FIG. 2 is a plan view illustrating the vibrator element of the physicalquantity detection element 100 according to the embodiment. The physicalquantity detection element 100 includes, for example, a double T typevibrator element formed by a Z-cut quartz crystal substrate. In thevibrator element formed using quartz crystal as a material, a variationin a resonance frequency to a temperature change is considerably small.There is the advantage of improving detection accuracy of an angularvelocity. In FIG. 2, X, Y, and Z axes are illustrated as quartz crystalaxes.

As illustrated in FIG. 2, in the vibrator element of the physicalquantity detection element 100, drive vibration arms 101 a and 101 bextend from two drive base portions 104 a and 104 b in the +Y axisdirection and the −Y axis direction. Drive electrodes 112 and 113 arerespectively formed on the side and upper surfaces of the drivevibration arms 101 a, and drive electrodes 113 and 112 are respectivelyformed on the side and upper surfaces of the drive vibration arms 101 b.The drive electrodes 112 and 113 are respectively connected to a drivecircuit 20 via DS and DG terminals of the physical quantity detectioncircuit 200 illustrated in FIG. 1.

The drive base portions 104 a and 104 b are connected to a rectangulardetection base portion 107 via connection arms 105 a and 105 b extendingin the −X axis direction and the +X axis direction, respectively.

Detection vibration arms 102 extend from the detection base portion 107in the +Y axis direction and the −Y axis direction. Detection electrodes114 and 115 are formed on the upper surfaces of the detection vibrationarms 102 and common electrodes 116 are formed on the side surfaces ofthe detection vibration arms 102. The detection electrodes 114 and 115are respectively connected to a detection circuit 30 via S1 and S2terminals of the physical quantity detection circuit 200 illustrated inFIG. 1. The common electrodes 116 are grounded.

When an alternating-current voltage is a given as a drive signal betweenthe drive electrodes 112 and the drive electrodes 113 of the drivevibration arms 101 a and 101 b, as illustrated in FIG. 3, the drivevibration arms 101 a and 101 b perform flexural vibration (excitationvibration) in such a manner that the front ends of the two drivevibration arms 101 a and 101 b repeatedly approach and separatemutually, as indicated by arrows B by an inverse piezoelectric effect.

In this state, when an angular velocity is applied to the vibratorelement of the physical quantity detection element 100 using the Z axisas a rotation axis, the drive vibration arms 101 a and 101 b obtain theCoriolis force in a direction perpendicular to both of the direction ofthe flexural vibration indicated by the arrows B and the Z axis. As aresult, as illustrated in FIG. 4, the connection arms 105 a and 105 bvibrate, as indicated by arrows C. The detection vibration arms 102perform flexural vibration, as indicated by arrows D, in linkage withthe vibration (indicated by the arrows C) of the connection arms 105 aand 105 b. The phases of the flexural vibration of the detectionvibration arms 102 accompanied with the Coriolis force and the flexuralvibration (excitation vibration) of the drive vibration arms 101 a and101 b are deviated by 90°.

Incidentally, when the magnitudes of vibration energies or themagnitudes of the amplitudes of the vibration at the time of theflexural vibration (excitation vibration) of the drive vibration arms101 a and 101 b are the same between the two drive vibration arms 101 aand 101 b, the vibration energies of the drive vibration arms 101 a and101 b are balanced. Thus, in a state in which no angular velocity isapplied to the physical quantity detection element 100, the detectionvibration arms 102 do not perform flexural vibration. Incidentally, whenthe balance of the vibration energies of the two drive vibration arms101 a and 101 b is collapsed, the flexural vibration is generated in thedetection vibration arms 102 even in a state in which no angularvelocity is applied to the physical quantity detection element 100. Thisflexural vibration is referred to as leakage vibration and is flexuralvibration indicated by the arrows D as in the vibration based on theCoriolis force, but the has the same phase as the drive signal.

Alternating-current charges based on the flexural vibration aregenerated in the detection electrodes 114 and 115 of the detectionvibration arms 102 by a piezoelectric effect. Here, thealternating-current charges generated based on the Coriolis force arechanged according to the magnitude of the Coriolis force (in otherwords, the magnitude of the angular velocity applied to the physicalquantity detection element 100). On the other hand, thealternating-current charges generated based on the leakage vibration areconstant regardless of the magnitude of the angular velocity applied tothe physical quantity detection element 100.

Rectangular weight portions 103 with widths wider the drive vibrationarms 101 a and 101 b are formed at the front ends of the drive vibrationarms 101 a and 101 b. By forming the weight portions 103 at the frontends of the drive vibration arms 101 a and 101 b, it is possible toincrease the Coriolis force and it is possible to obtain vibration armswith relatively short desired resonance frequency. Similarly,rectangular weight portions 106 with widths wider than the detectionvibration arms 102 are formed at the front ends of the detectionvibration arms 102. By forming the weight portions 106 at the front endsof the detection vibration arms 102, it is possible to increasealternating-current charges generated in the detection electrodes 114and 115.

In this way, the physical quantity detection element 100 outputs thealternating-current charge (a vibration leakage component) based onleakage vibration of the excitation vibration and thealternating-current charge (an angular velocity component) based on theCoriolis force, using the Z axis as a detection axis, via the detectionelectrodes 114 and 115. The physical quantity detection element 100functions as an inertial sensor that detects an angular velocity.

Referring back to FIG. 1, the physical quantity detection circuit 200according to the embodiment is configured to include a reference voltagecircuit 10, the drive circuit 20, the detection circuit 30, a dataprocessing circuit 40, a storage unit 50, and an oscillation circuit 60.The physical quantity detection circuit 200 may be, for example, anintegrated circuit (IC) of one chip. The physical quantity detectioncircuit 200 according to the embodiment may be configured such that someof these elements may be omitted or changed or other elements may beadded.

The reference voltage circuit 10 generates a constant voltage or aconstant current such as a reference voltage (analog ground voltage)from a power supply voltage supplied from a VDD terminal of the physicalquantity detection circuit 200 and supplies the constant voltage or theconstant current to the drive circuit 20 or the detection circuit 30.

The drive circuit 20 generates a drive signal to perform excitationvibration on the physical quantity detection element 100 and suppliesthe drive signal to the drive electrodes 112 of the physical quantitydetection element 100 via a DS terminal. An oscillation currentgenerated in the drive electrodes 113 by the excitation vibration of thephysical quantity detection element 100 is input via a DG terminal, andthe drive circuit 20 performs feedback control of an amplitude level ofthe drive signal so that the amplitude of the oscillation current ismaintained constantly. The drive circuit 20 generates a detection signalSDET with the same phase as the drive signal and outputs the detectionsignal SDET to the detection circuit 30.

The alternating-current charges (detection currents) generated in thetwo detection electrodes 114 and 115 of the physical quantity detectionelement 100 are input via S1 and S2 terminals, and the detection circuit30 detects the angular velocity component included in thealternating-current charges (detection currents) using the detectionsignal SDET, and generates and outputs a signal (angular velocitysignal) VAO with a voltage level according to the magnitude of theangular velocity component.

The storage unit 50 includes a nonvolatile memory (not illustrated). Thenonvolatile memory stores various kinds of trimming data (adjustmentdata or correction data) for the drive circuit 20 or the detectioncircuit 30. The nonvolatile memory can be configured as, for example, ametal oxide nitride oxide silicon (MONOS) memory or an electricallyerasable programmable read-only memory (EEPROM). The storage unit 50 mayfurther include a register (not illustrated) and may be configured suchthat the various kinds of trimming data stored in the nonvolatile memoryare transmitted to the register and maintained when power is supplied tothe physical quantity detection circuit 200 (when the voltage of the VDDterminal rises from 0 V to a desired voltage), and the various kinds oftrimming data maintained in the register are supplied to the drivecircuit 20 or the detection circuit 30.

The data processing circuit 40 is configured to include a digitalcalculation circuit 41 and an interface circuit 42.

The digital calculation circuit 41 operates by a master clock signalMCLK, converts the voltage level of the angular velocity signal VAOoutput by the detection circuit 30 into a digital value, subsequentlyperforms an interpolation process based on a timing at which a readingrequest signal REQ is input, and outputs interpolated data obtainedthrough the interpolation process as digital data VDO.

The interface circuit 42 performs a process of outputting the readingrequest signal REQ according to a communication signal transmitted by amicro control unit (MCU) 2 (which is an example of a control device)which is an external device of the physical quantity detection circuit200 and a process of outputting the digital data VDO (interpolated data)output by the digital calculation circuit 41 to the MCU 2. The interfacecircuit 42 performs, for example, a process of reading data stored inthe storage unit 50 (the nonvolatile memory or the register) in responseto a request from the MCU 2 and outputting the data to the MCU 2 or aprocess of writing the data input from the MCU 2 on the storage unit 50(the nonvolatile memory or the register). The interface circuit 42 is,for example, an interface circuit of a serial peripheral interface (SPI)bus. A selection signal, a clock signal, and a data signal which arecommunication signals transmitted by the MCU 2 are respectively inputvia SS, SCLK, and SI terminals of the physical quantity detectioncircuit 200 and the data signal is output to the MCU 2 via an SOterminal of the physical quantity detection circuit 200. The interfacecircuit 42 may be an interface circuit corresponding to any of variousbuses (for example, an inter-integrated circuit (I²C) bus) other thanthe SPI bus.

The oscillation circuit 60 functions as a clock generation circuit thatgenerates the master clock signal MCLK and outputs the master clocksignal MCLK to the digital calculation circuit 41 included in the dataprocessing circuit 40. The oscillation circuit 60 is configured as, forexample, a ring oscillator or a CR oscillation circuit.

Configuration of Drive Circuit

Next, the drive circuit 20 will be described. FIG. 5 is a diagramillustrating an example of the configuration of the drive circuit 20. Asillustrated in FIG. 5, the drive circuit 20 according to the embodimentis configured to include an I/V conversion circuit 21, a highpass filter(HPF) 22, a comparator 23, a full-wave rectification circuit 24, anintegrator 25, and a comparator 26. The drive circuit 20 according tothe embodiment may be configured such that some of these elements may beomitted or changed or other elements may be added.

The I/V conversion circuit 21 converts the oscillation current generatedby the excitation vibration of the physical quantity detection element100 and input via the DG terminal into an alternating-current voltagesignal.

The highpass filter 22 removes an offset of the output signal of the I/Vconversion circuit 21.

The comparator 23 generates a binary signal by comparing the voltage ofthe output signal of the highpass filter 22 to the reference voltage,electrifies an NMOS transistor and outputs a low level when the binarysignal is at a high level, does not electrify the NMOS transistor whenthe binary signal is at a low level, and outputs the output voltage ofthe integrator 25 pulled up via a resistor as the high level. Then, theoutput signal of the comparator 23 is supplied as a drive signal to thephysical quantity detection element 100 via the DS terminal. By matchingthe frequency (drive frequency) of the drive signal with the resonancefrequency of the physical quantity detection element 100, it is possibleto stably oscillate the physical quantity detection element 100.

The full-wave rectification circuit 24 rectifies (performs full-waverectification on) the output signal of the I/V conversion circuit 21 andoutputs the direct-current signal.

The integrator 25 integrates the output voltage of the full-waverectification circuit 24 using a desired voltage VRDR supplied from thereference voltage circuit 10 as a reference and outputs the outputvoltage. The output voltage of the integrator 25 is lower as the outputof the full-wave rectification circuit 24 is high (as the amplitude ofthe output signal of the I/V conversion circuit 21 is larger).Accordingly, as an oscillation amplitude is larger, the voltage with thehigh level of the output signal (drive signal) of the comparator 23 islower. As the oscillation amplitude is smaller, the voltage with thehigh level of the output signal (drive signal) of the comparator 23 ishigher. Therefore, an auto gain control (AGC) is applied so that theoscillation amplitude is maintained constantly.

The comparator 26 generates a binary signal (square wave voltage signal)by amplifying the voltage of the output signal of the highpass filter 22and outputs the binary signal as the detection signal SDET.

Configuration of Detection Circuit

Next, the detection circuit 30 will be described. FIG. 6 is a diagramillustrating an example of the configuration of the detection circuit30. As illustrated in FIG. 6, the detection circuit 30 according to theembodiment is configured to include charge amplifiers 31 and 32, adifferential amplifier 33, a highpass filter (HPF) 34, an AC amplifier35, a synchronization detection circuit 36, a variable gain amplifier37, a switched capacitor filter (SCF) 38, and an output buffer 39. Thedetection circuit 30 according to the embodiment may be configured suchthat some of these elements may be omitted or changed, or other elementsmay be added.

The alternating-current charge (detection current) including the angularvelocity component and the vibration leakage component is input from thedetection electrode 114 of the vibrator element of the physical quantitydetection element 100 to the charge amplifier 31 via the S1 terminal.Similarly, the alternating-current charge (detection current) includingthe angular velocity component and the vibration leakage component isinput from the detection electrode 115 of the vibrator element of thephysical quantity detection element 100 to the charge amplifier 32 viathe S2 terminal.

The charge amplifiers 31 and 32 convert the input alternating-currentcharges (detection currents) into alternating-current voltage signals.The phase of the alternating-current charge (detection current) input tothe charge amplifier 31 is different by 180° from the phase of thealternating-current charge (detection current) input to the chargeamplifier 32. The phase of the output signal of the charge amplifier 31and the phase of the output signal of the charge amplifier 32 arereverse (deviated by 180°).

The differential amplifier 33 performs differential amplification on theoutput signal of the charge amplifier 31 and the output signal of thecharge amplifier 32. An in-phase component is cancelled by thedifferential amplifier 33 and a reverse-phase component is added andamplified.

The highpass filter 34 removes a direct-current component included inthe output signal of the differential amplifier 33.

The AC amplifier 35 outputs an alternating-current voltage signalobtained by amplifying the output signal of the highpass filter 34.

The synchronization detection circuit 36 performs synchronizationdetection on the angular velocity component included in the outputsignal (detected signal) of the AC amplifier 35, using the detectionsignal SDET output by the drive circuit 20. For example, thesynchronization detection circuit 36 can be configured as a circuit thatselects the output signal of the AC amplifier 35 without change when thedetection signal SDET is at the high level and selects a signal invertedfrom the output signal of the AC amplifier 35 with respect to thereference voltage when the detection signal SDET is at the low level.

The output signal of the AC amplifier 35 includes the angular velocitycomponent and the vibration leakage component. The angular velocitycomponent has the same phase as the detection signal SDET whereas havingthe reverse phase to the vibration leakage component. Therefore, theangular velocity component is subjected to the synchronization detectionby the synchronization detection circuit 36, but the vibration leakagecomponent is not detected.

The variable gain amplifier 37 amplifies or attenuates the output signalof the synchronization detection circuit 36 and outputs a signal with adesired voltage level, and the output signal of the variable gainamplifier 37 is input to the switched capacitor filter (SCF) 38.

The switched capacitor filter (SCF) 38 functions as a lowpass filterthat removes a high-frequency component included in the output signal ofthe variable gain amplifier 37 and passes a signal of a frequency rangedecided in the specification. The frequency characteristics of theswitched capacitor filter (SCF) 38 (lowpass filter) are decided by thefrequency of a clock signal (not illustrated) obtained by stableoscillation of the physical quantity detection element 100 and acapacitance ratio of a capacitor (not illustrated). Therefore, there isthe advantage in which a variation in the frequency characteristics isconsiderably smaller than in an RC lowpass filter.

The output signal of the switched capacitor filter (SCF) 38 is bufferedby the output buffer 39 and is amplified or attenuated to a signal witha desired voltage level, as necessary. The output signal of the outputbuffer 39 is output as the angular velocity signal VAC from thedetection circuit 30.

Configuration of Data Processing Circuit

Next, the details of the data processing circuit 40 will be described.FIG. 7 is a diagram illustrating an example of the configuration of thedata processing circuit 40. As illustrated in FIG. 1, the dataprocessing circuit 40 according to the embodiment is configured toinclude the digital calculation circuit 41 and the interface circuit 42.As illustrated in FIG. 7, the digital calculation circuit 41 isconfigured to include an A/D conversion circuit 43, a digital filtercircuit 44, an interpolation circuit 45, and a sampling clock generationcircuit 46. The digital calculation circuit 41 according to theembodiment may be configured such that some of these elements may beomitted or changed, or other elements may be added.

The sampling clock generation circuit 46 generates a sampling clocksignal ADCLK based on the master clock signal MCLK (the output signal ofthe oscillation circuit 60) and outputs the sampling clock signal ADCLK.

The A/D conversion circuit 43 samples the angular velocity signal VACoutput by the detection circuit 30 in synchronization with the samplingclock signal ADCLK, converts a sampled voltage value into digital data,and outputs the digital data.

The signal (digital data) from the A/D conversion circuit 43 is input,and the digital filter circuit 44 performs a process of filtering thedigital data in synchronization with the master clock signal MCLK.

The interpolation circuit 45 is a circuit that performs theinterpolation process on the input digital signal (the digital signalfrom the digital filter circuit 44) and outputs interpolated datasubjected to the interpolation process. In the embodiment, the interfacecircuit 42 outputs the reading request signal REQ making a request foroutputting the interpolated data according to the input communicationsignals. The reading request signal REQ is input, and interpolationcircuit 45 performs the interpolation process based on the digitalsignal input earlier than a timing at which the reading request signalREQ.

The interpolation circuit 45 outputs the interpolated data in responseto the reading request signal REQ. The interpolated data is output asthe digital data VDO to the outside of the data processing circuit 40via the interface circuit 42.

The interpolation circuit 45 may perform the interpolation process basedon a time from the input timing of the digital signal from the digitalfilter circuit 44 to the input timing of the reading request signal REQand the plurality of digital signals input earlier than the input timingof the digital signal.

For example, the interpolation circuit 45 may perform the interpolationprocess by a Bi-Cubic method (cubic interpolation method). FIG. 8 is adiagram illustrating the Bi-Cubic method. As illustrated in FIG. 8, theinterpolation circuit 45 sets input data (the digital signal from thedigital filter circuit 44) more recently input with respect to the inputtiming of the reading request signal REQ to x₃, sets input data inputbefore one more sampling period (corresponding to one period of thesampling clock signal ADCLK) of the reading request signal REQ to x₂,sets input data input before further one more sampling period of thereading request signal REQ to x₁, and sets input data input before stillfurther one more sampling period of the reading request signal REQ tox₀. A time obtained by normalizing the time from the recently data inputtiming to the input timing of the reading request signal REQ as 1 at onesampling period is assumed to be d (0≤d<1). At this time, theinterpolation circuit 45 performs the interpolation process byexpression (1) of the Bi-Cubic method using the pieces of input data x₀,x₁, x₂, and x₃ to calculate interpolated data y at a timing later by thetime d from the data input timing of the input data x₁.y=x ₀ ·h ₁(d+1)+x ₁ ·h ₂(d)+x ₂ ·h ₂(1−d)+x ₃ ·h ₁(2−d)  (1)

In Expression (1), h₁(d) and h₂(d) are indicated in Expressions (2) and(3), respectively.h ₁(d)=(a+2)·d ³−(a+3)·d ²+1  (2)h ₂(d)=a·d ³−5a·d ²+8a·d−4a  (3)

In Expressions (2) and (3), a is any coefficient and a value in therange of −0.5 to −1.0 is generally used. Here, a small value (−0.5) ofan absolute value is preferable to proliferate harmonic distortionoccurring in the interpolated data y. Accordingly, when Expressions (2)and (3) are substituted to Expressions (1) as a=−0.5 for modification,Expression (4) is obtained.

$\begin{matrix}{y = {{\left( {{{- 0.5}x_{0}} + {1.5x_{1}} - {1.5x_{2}} + {0.5x_{3}}} \right)d^{3}} + {\left( {x_{0} - {2.5x_{1}} + {2x_{2}} - {0.5x_{3}}} \right)d^{2}} + {\left( {{{- 0.5}x_{0}} + {0.5x_{2}}} \right)d} + x_{1}}} & (4)\end{matrix}$

In the embodiment, the interpolation circuit 45 is configured to includea counter 47, a calculation circuit 48, and a lookup table 49 in orderto perform the interpolation process in accordance with the Bi-Cubicmethod.

The counter 47 is a counter that counts up from 0 to SR−1 during onesampling period (one period of the sampling clock signal ADCLK) insynchronization with the master clock signal MCLK. The SR corresponds toa frequency ratio of the master clock signal MCLK to the sampling clocksignal ADCLK.

FIG. 9 is a diagram illustrating examples of timing charts of the masterclock signal MCLK, an output signal CNT of the counter 47, the samplingclock signal ADCLK, and the reading request signal REQ. As illustratedin the timing charts of FIG. 9, when n is the value of the output signalCNT of the counter 47 at the input timing of the reading request signalREQ, the time d illustrated in FIG. 8 is expressed in Expression (5)using n and SR.

$\begin{matrix}{d = \frac{n}{SR}} & (5)\end{matrix}$

Accordingly, when Expression (5) is substituted to Expression (4) formodification, Expression (6) is obtained.

$\begin{matrix}{y = {x_{1} + {\frac{x_{2} - x_{0}}{2} \cdot \frac{n}{SR}} + {K_{0} \cdot x_{0}} + {K_{1} \cdot x_{1}} + {K_{2} \cdot x_{2}} + {K_{3} \cdot x_{3}}}} & (6)\end{matrix}$

In Expression (6), coefficients K₀, K₁, K₂, and K₃ are indicated inExpressions (7), (8), (9), and (10), respectively.

$\begin{matrix}{K_{0} = {{{- \frac{1}{2}}\left( \frac{n}{SR} \right)^{3}} + \left( \frac{n}{SR} \right)^{2}}} & (7) \\{K_{1} = {{\frac{3}{2}\left( \frac{n}{SR} \right)^{3}} - {\frac{5}{2}\left( \frac{n}{SR} \right)^{2}}}} & (8) \\{K_{2} = {{{- \frac{3}{2}}\left( \frac{n}{SR} \right)^{3}} + {2\left( \frac{n}{SR} \right)^{2}}}} & (9) \\{K_{3} = {{\frac{1}{2}\left( \frac{n}{SR} \right)^{3}} - {\frac{1}{2}\left( \frac{n}{SR} \right)^{2}}}} & (10)\end{matrix}$

In the embodiment, the lookup table 49 stores data related to a relationbetween a calculation coefficient of the interpolation process and atiming d at which the reading request signal REQ is input. Specifically,as illustrated in FIG. 10, the range of 0 to SR−1 in which the value ofthe output signal CNT of the counter 47 is allowed is divided into aplurality of ranges (0 to n₁−1, n₁ to n₂−1, n₂ to n₃−1, etc.). Then, arelation between each range of the value of the CNT and each value ofthe coefficients K₀, K₁, K₂, and K₃ is stored in the lookup table 49.

The calculation circuit 48 calculates the values of Expression (6) withthe coefficients K₀, K₁, K₂, and K₃ in the third to sixth terms(Bi-Cubic interpolation terms) of the right side of Expression (6)determined according to the lookup table 49. In this case, calculationof Expressions (7), (8), (9), and (10) is not necessary.

In the embodiment, the calculation circuit 48 is realized bycontinuously calculating multiplication of the second term (linearinterpolation term) of the right side of Expression (6) and eachmultiplication of the third to sixth terms (Bi-Cubic interpolationterms) of the right side using each adder at all times. Accordingly, itis possible to reduce the circuit size of the calculation circuit 48 andit is possible to output the interpolated data y as the digital data VDOimmediately in response to the reading request signal REQ input atasynchronous timing with the sampling clock signal ADCLK.

Advantages

In the physical quantity detection device 1 (the data processing circuit40) according to the first embodiment, the interpolation circuit 45outputs the digital data VDO subjected to the interpolation processaccording to the time d from the input timing (sampling timing) of thedigital signal to the input timing of the reading request signal REQ.Specifically, as illustrated in FIG. 8, the interpolation circuit 45performs the interpolation process by the Bi-Cubic method using therecent input data x₃, the input data x₂ before one sampling period, theinput data x₁ before two sampling periods, and the input data x₀ beforethree sampling periods according to the time d from the input timing ofthe recent input data x₃ to the input timing of the reading requestsignal REQ, generates the interpolated data Y later by the time d fromthe input data x₁ before two sampling periods, and outputs theinterpolated data y as the digital data VDO. The digital data VDO (theinterpolated data y) is output later by two periods of the samplingperiod of the A/D conversion circuit 43, but is data which is sampled bythe A/D conversion circuit 43 to be subjected to A/D conversion insynchronization with the input timing of the reading request signal REQand indicates data subjected to the filtering process by the digitalfilter circuit 44 in a pseudo-manner. Accordingly, the physical quantitydetection device 1 (the data processing circuit 40) according to thefirst embodiment can reduce occurrence of folding noise to the digitaldata VDO even when the sampling timing (the input timing of the digitalsignal to the interpolation circuit 45) by the A/D conversion circuit 43is asynchronous with the reading request timing (the input timing of thereading request signal REQ) from the MCU 2.

1-2. Second Embodiment

In the physical quantity detection device 1 (the data processing circuit40) according to the first embodiment, in order for the interpolationcircuit 45 to output the interpolated data y in immediate response tothe reading request signal REQ, the calculation circuit 48 necessarilyperforms addition at all times (performs the interpolation process atall times). Therefore, power consumption is considerable. In contrast,in a physical quantity detection device 1 according to a secondembodiment, an interpolation circuit 45 performs an interpolationprocess in response to a reading request signal REQ. That is, theinterpolation circuit 45 completes a correction process in one period ofthe master clock signal MCLK at an input timing of the reading requestsignal REQ and immediately outputs interpolated data y. Hereinafter, thesame reference numerals are given to the same configurations as thefirst embodiment. Differences from the first embodiment will bedescribed omitting the repeated description as the first embodiment.

The interpolation circuit 45 according to the second embodiment isconfigured to include a counter 47, a calculation circuit 48, and alookup table 49 in order to perform an interpolation process by aBi-Cubic method, as in the first embodiment (see FIG. 7).

As in the first embodiment, the counter 47 is a counter that counts upfrom 0 to SR−1 during one sampling period (one period of the samplingclock signal ADCLK) in synchronization with the master clock signalMCLK.

As illustrated in FIG. 11, the calculation circuit 48 has four-stepcalculation stages. Each calculation stage i (where i=1 to 4) isconfigured to include two selectors nai and nsi that select one piece ofdata from four pieces of input data x₃, x₂, x₁, and x₀ output by a shiftregister, an adder-subtracter that subtracts mutual selected signals,and a calculator that performs bit shift of any amount. The calculationcircuit 48 adds the output signals of the calculation stages by theadders to generate the interpolated data y.

The lookup table 49 stores data related to a relation between acalculation coefficient of the interpolation process and a timing d atwhich the reading request signal REQ is input. Specifically, asillustrated in FIG. 12, the range of 0 to SR−1 in which the value of theoutput signal CNT of the counter 47 is allowed is divided into aplurality of ranges (0 to n₁−1, n₁ to n₂−1, n₂ to n₃−1, etc.). Then, arelation between each range of the value of the CNT, and selectedsignals of two selectors included in each calculation stage of thecalculation circuit 48 and a bit shift amount of the calculator isstored in the lookup table 49.

The calculation circuit 48 can generate the interpolated data y in oneperiod of the master clock signal MCLK by calculating the values of thecoefficients of d³, d², and d of the right side of Expression (4) in thefour calculation stages with reference to the lookup table 49.Accordingly, it is possible to reduce the circuit size of thecalculation circuit 48 and it is possible to output the interpolateddata y as the digital data VDO immediately in response to the readingrequest signal REQ input at asynchronous timing with the sampling clocksignal ADCLK.

As in the first embodiment, the physical quantity detection device 1(the data processing circuit 40) according to the second embodiment canreduce occurrence of folding noise to the digital data VDO even when thesampling timing (the input timing of the digital signal to theinterpolation circuit 45) by the A/D conversion circuit 43 isasynchronous with the reading request timing (the input timing of thereading request signal REQ) from the MCU 2.

Further, in the physical quantity detection device 1 (the dataprocessing circuit 40) according to the second embodiment, theinterpolation circuit 45 can start the interpolation process in responseto the reading request signal REQ and output the digital data VDO (theinterpolated data y) immediately (after one period of the master clocksignal) by configuring the calculation circuit 48 as in FIG. 11 andconfiguring the lookup table 49 as in FIG. 12. Accordingly, in thephysical quantity detection device 1 (the data processing circuit 40),it is not necessary for the calculation circuit 48 to perform theinterpolation process at all times. Therefore, it is possible to reducepower consumption.

2. Electronic Apparatus

FIG. 13 is a functional block diagram illustrating an example of theconfiguration of an electronic apparatus according to an embodiment. Asillustrated in FIG. 13, an electronic apparatus 300 according to anembodiment is configured to include a physical quantity detection device310, a control device (MCU) 320, an operation unit 330, a read-onlymemory (ROM) 340, a random access memory (RAM) 350, a communication unit360, and a display unit 370. The electronic apparatus according to theembodiment may be configured such that some of these constituentelements (units) in FIG. 13 may be omitted or changed, or other elementsmay be added.

The physical quantity detection device 310 is a device that detects aphysical quantity based on an analog signal related to a physicalquantity output by a physical quantity detection element (notillustrated) and outputs digital data according to the detected physicalquantity. The physical quantity detection device 310 may be, forexample, an inertial measurement device that detects at least some ofphysical quantities such as acceleration, an angular velocity, avelocity, angular acceleration, and a force or may be an inclinometerthat measures an inclination angle. As the physical quantity detectiondevice 310, for example, the physical quantity detection device 1according to the above-described embodiment can be applied. The physicalquantity detection device 310 is configured to include a data processingcircuit 312. As the data processing circuit 312, for example, the dataprocessing circuit 40 according to the above-described embodiment can beapplied.

The control device (MCU) 320 transmits a communication signal to thephysical quantity detection device 310 according to a program stored inthe ROM 340 or the like and performs various calculation processes orcontrol processes using output data of the physical quantity detectiondevice 310. Additionally, the control device (MCU) 320 performs, forexample, various processes according to operation signals from theoperation unit 330, a process of controlling the communication unit 360to perform data communication with an external device, and a process oftransmitting display signals to display various kinds of information onthe display unit 370.

The operation unit 330 is an input device configured to include anoperation key and a button switch and outputs an operation signalaccording to a manipulation performed by a user to the control device(MCU) 320.

The ROM 340 stores programs, data, or the like used for the controldevice (MCU) 320 to perform various calculation processes or controlprocesses.

The RAM 350 is used as a work area of the control device (MCU) 320 andtemporarily stores, for example, programs or data read from the ROM 340,data input from the operation unit 330, and calculation results or thelike processed according to various programs by the control device (MCU)320.

The communication unit 360 performs various controls to establish datacommunication between the control device (MCU) 320 and an externaldevice.

The display unit 370 is a display device configured to include a liquidcrystal display (LCD) and displays various kinds of information based ondisplay signals input from the CPU 320. The display unit 370 may includea touch panel functioning as the operation unit 330.

By applying, for example, the physical quantity detection device 1according to the above-described embodiment as the physical quantitydetection device 310 or applying, for example, the data processingcircuit 40 according to the above-described embodiments as the dataprocessing circuit 312 included in the physical quantity detectiondevice 310, it is possible to realize an electronic apparatus with highreliability.

As the electronic apparatus 300, various electronic apparatuses can beconsidered. Examples of the electronic apparatus 300 include a personalcomputer (for example, a mobile personal computer, a laptop personalcomputer, or a tablet personal computer), a moving object terminal suchas a smartphone or a portable telephone, a digital camera, an ink jetejection apparatus (for example, an ink jet printer), a storage areanetwork apparatus such as a router or a switch, a local area networkapparatus, a mobile station terminal base station apparatus, atelevision, a video camera, a video recorder, a car navigationapparatus, a real-time clock apparatus, a pager, an electronic organizer(also including a communication function unit), an electronicdictionary, a calculator, an electronic game apparatus, a gamecontroller, a word processor, a workstation, a television telephone, amonitoring television monitor, electronic binoculars, a POS terminal, amedical apparatus (for example, an electronic thermometer, ablood-pressure meter, a blood-sugar meter, an electrocardiographicapparatus, an ultrasonic diagnosis apparatus, and an electronicendoscope), a fish finder, various measurement apparatuses, meters (forexample, meters of vehicles, airplanes, and ships), a flight simulator,a head-mounted display, a motion tracing apparatus, a motion trackingapparatus, a motion controller, and a pedestrian dead reckoning (PDR)apparatus.

FIG. 14 is a perspective view schematically illustrating a digital stillcamera 1300 which is an example of the electronic apparatus 300according to the embodiment. In FIG. 14, connection with an externalapparatus is also simply illustrated. Here, a normal camera exposes asilver-salt photo film by a light image of a subject, but the digitalcamera 1300 performs photoelectric conversion on a light image of asubject using an image sensor such as a charge coupled device (CCD) andgenerate an imaging signal (image signal).

In the digital camera 1300, a display unit 1310 is installed on the rearsurface of a case (body) 1302 to perform display based on the imagingsignal generated by the CCD. The display unit 1310 functions as a finderthat displays a subject as an electronic image. A light-receiving unit1304 including an optical lens (imaging optical system) or a CCD isinstalled on the front surface (the rear surface side of the drawing) ofthe case 1302. When a photographer confirms a subject image displayed onthe display unit 1310 and presses a shutter button 1306, an imagingsignal of the CCD at that time is transmitted and stored in a memory1308. In the digital camera 1300, a video signal output terminal 1312and a data communication input/output terminal 1314 are provided on aside surface of the case 1302. As illustrated, a television monitor 1430is connected to the video signal output terminal 1312 and a personalcomputer 1440 is connected to the data communication input/outputterminal 1314, as necessary. The imaging signal stored in the memory1308 is configured to be output to the television monitor 1430 or thepersonal computer 1440 through a predetermined operation. The digitalcamera 1300 includes the physical quantity detection device 310 andperforms, for example, a process such as camera-shake correction usingoutput data of the physical quantity detection device 310.

3. Moving Object

FIG. 15 is a diagram (top view) illustrating an example of a movingobject according to an embodiment. A moving object 400 illustrated inFIG. 15 is configured to include physical quantity detection devices410, 420, and 430, controllers 440, 450, and 460, a battery 470, and anavigation device 480. The moving object according to the embodiment maybe configured such that some of these elements (units) in FIG. 15 may beomitted or changed, or other elements may be added.

The physical quantity detection devices 410, 420, and 430, thecontrollers 440, 450, and 460, and the navigation 480 operate with apower supply voltage supplied from the battery 470.

The controllers 440, 450, and 460 are control devices that transmitcommunication signals to the physical quantity detection devices 410,420, and 430, respectively, and perform various kinds of control of aposture control system, a rollover prevention system, a brake system,and the like using output data of the physical quantity detectiondevices 410, 420, and 430.

The navigation device 480 displays the position of the moving object400, a time, and other various kinds of information based on outputinformation of an included GPS receiver (not illustrated) on a display.The navigation device 480 includes a physical quantity detection device490, and thus continuously displays necessary information by calculatingthe position or the direction of the moving object 400 based on anoutput signal of the physical quantity detection device 490 even whenGPS radio waves do not arrive.

The physical quantity detection devices 410, 420, 430, and 490 aredevices that detect physical quantities based on analog signals relatedto the physical quantities output by physical quantity detectionelements (not illustrated) and output digital data according to thedetected physical quantities. For example, an angular velocity sensor,an acceleration sensor, and a velocity sensor, and an inclinometer areused.

For example, the physical quantity detection device 1 according to theabove-described embodiments can be applied as the physical quantitydetection devices 410, 420, 430, and 490 or the data processing circuit40 according to the above-described embodiments can be applied as dataprocessing circuits (not illustrated) included in the physical quantitydetection devices 410, 420, 430, and 490, so that a moving object withhigh reliability can be realized.

Various moving objects can be considered as the moving object 400. Forexample, an automobile (also including an electric automobile), anairplane such as a jet plane or a helicopter, a ship, a rocket, and anartificial satellite can be exemplified.

The invention is not limited to the embodiments, various modificationscan be made within the scope of the gist of the invention.

For example, in the above-described embodiments, the interpolationcircuit 45 performs the interpolation process by the Bi-Cubic method.However, in addition to the Bi-Cubic method, various methods such as anearest neighbor method (a nearest neighbor interpolation method or amost adjacent interpolation method), a bilinear method (linearinterpolation method), and a Lanczos method can be used.

In the above-described embodiments, the angular velocity detectiondevice including the physical quantity detection element 100 detectingan angular velocity has been exemplified in the description. However,the invention can also be applied to physical quantity detection devicesincluding physical quantity detection elements detecting variousphysical quantities. The physical quantity detected by the physicalquantity detection element is not limited to an angular velocity, butmay be angular acceleration, acceleration, a velocity, a force, or thelike. The vibrator element of the physical quantity detection elementmay not be of the double T type, but may be, for example, of a tuningfork type, a sinking comb type, or a tuning bar type with a triangularprism, a quadrangular prism, a columnar shape, or the like. As thematerial of the vibrator element of the physical quantity detectionelement, instead of quartz crystal (SiO₂), for example, a piezoelectricmaterial such as a piezoelectric single crystal such as lithiumtantalate (LiTaO₃) or lithium niobate (LiNbO₃) or a piezoelectricceramics such as lead zirconate titanate (PZT) may be used, or a siliconsemiconductor may be used. For example, a piezoelectric thin film ofzinc oxide (ZnO) or aluminum nitride (AlN) interposed between driveelectrodes may be disposed in a part of the surface of a siliconsemiconductor. The physical quantity detection element is not limited tothe piezoelectric type element, but may be a vibration type element suchas an electrodynamic type, an electrostatic capacitance type, aneddy-current type, an optical type, a strain gage type. Alternatively,the method of the physical quantity detection element is not limited toa vibration type, but may be an optical type, a rotation type, or afluid type.

The above-described embodiments and modification examples are merelyexamples and the invention is not limited thereto. For example, theembodiments and the modification examples can also be appropriatelycombined.

The invention includes substantially the same configurations (forexample, configurations in which the functions, the methods, and theresults are the same or configurations in which the goals and theadvantages are the same) as the configurations described in theembodiments. The invention includes configurations in which unessentialportions of the configurations described in the embodiments aresubstituted. The invention includes configurations in which the sameoperation and advantages as the configurations described in theembodiments or configurations in which the same goals can be achieved.The invention includes configurations in which known technologies areadded to the configurations described in the embodiments.

The entire disclosure of Japanese Patent Application No. 2015-059326,filed Mar. 23, 2015 is expressly incorporated by reference herein.

What is claimed is:
 1. A data processing circuit comprising: aninterpolation circuit that performs an interpolation process on an inputdigital signal and outputs interpolated data subjected to theinterpolation process, wherein a reading request signal making a requestfor outputting the interpolated data is input, and the interpolationcircuit performs the interpolation process based on a plurality ofdigital signals input earlier than a timing at which the reading requestsignal is input, and a plurality of calculation coefficients of theinterpolation process is determined in accordance with the timing of thereading request signal, wherein each of the plurality of calculationcoefficients corresponds to respective ones of the plurality of digitalsignals input earlier than the timing at which the reading requestsignal is input.
 2. The data processing circuit according to claim 1,further comprising: an interface circuit, wherein the interface circuitoutputs the reading request signal according to an input communicationsignal, wherein the interpolation circuit outputs the interpolated datain response to the reading request signal, and wherein the interpolateddata is output via the interface circuit.
 3. The data processing circuitaccording to claim 2, wherein the interpolation circuit performs theinterpolation process based on a time from an input timing of thedigital signal to an input timing of the reading request signal and theplurality of the digital signals that input earlier than the inputtiming of the digital signal.
 4. The data processing circuit accordingto claim 3, wherein the interpolation circuit performs the interpolationprocess by a cubic interpolation method.
 5. The data processing circuitaccording to claim 2, wherein the interpolation circuit performs theinterpolation process by a cubic interpolation method.
 6. The dataprocessing circuit according to claim 1, wherein the interpolationcircuit performs the interpolation process based on a time from an inputtiming of the digital signal to an input timing of the reading requestsignal and the plurality of the digital signals that input earlier thanthe input timing of the digital signal.
 7. The data processing circuitaccording to claim 6, wherein the interpolation circuit performs theinterpolation process by a cubic interpolation method.
 8. The dataprocessing circuit according to claim 1, wherein the interpolationcircuit performs the interpolation process by a cubic interpolationmethod.
 9. The data processing circuit according to claim 1, wherein theinterpolation circuit performs the interpolation process in response tothe reading request signal.
 10. The data processing circuit according toclaim 1, wherein the interpolation circuit stores data related to arelation between one of the plurality of calculation coefficients of theinterpolation process and the timing at which the reading request signalis input.
 11. A physical quantity detection circuit comprising: an A/Dconversion circuit that performs A/D conversion on an analog signalrelated to a physical quantity; a digital filter circuit to which asignal from the A/D conversion circuit is input; an interpolationcircuit to which a digital signal from the digital filter circuit isinput, which performs an interpolation process on the digital signal, towhich a reading request signal making a request for outputtinginterpolated data subjected to the interpolation process is input, andwhich performs the interpolation process based on a plurality of digitalsignals input earlier than a timing at which the reading request signalis input; and an interface circuit that outputs the reading requestsignal according to an input communication signal, wherein theinterpolated data is output via the interface circuit, and a pluralityof calculation coefficients of the interpolation process is determinedin accordance with the timing of the reading request signal, whereineach of the plurality of calculation coefficients corresponds torespective ones of the plurality of digital signals input earlier thanthe timing at which the reading request signal is input.
 12. Thephysical quantity detection circuit according to claim 11, wherein theinterpolation circuit performs the interpolation process in response tothe reading request signal.
 13. The physical quantity detection circuitaccording to claim 12, wherein the interpolation circuit stores datarelated to a relation between one of the plurality of calculationcoefficients of the interpolation process and the timing at which thereading request signal is input.
 14. A physical quantity detectiondevice comprising: the physical quantity detection circuit according toclaim 12; and a physical quantity detection element, wherein the analogsignal is a signal output from the physical quantity detection element.15. The physical quantity detection circuit according to claim 11,wherein the interpolation circuit stores data related to a relationbetween one of the plurality of calculation coefficients of theinterpolation process and the timing at which the reading request signalis input.
 16. A physical quantity detection device comprising: thephysical quantity detection circuit according to claim 15; and aphysical quantity detection element, wherein the analog signal is asignal output from the physical quantity detection element.
 17. Aphysical quantity detection device comprising: the physical quantitydetection circuit according to claim 11; and a physical quantitydetection element, wherein the analog signal is a signal output from thephysical quantity detection element.
 18. The physical quantity detectiondevice according to claim 17, wherein the physical quantity detectionelement is an inertial sensor.
 19. An electronic apparatus comprising:the physical quantity detection device according to claim 17; and acontrol device that transmits the communication signal.
 20. A movingobject comprising: the physical quantity detection device according toclaim 17; and a control device that transmits the communication signal.